The present invention relates to an endoscopic instrument comprising a manipulating piece having a manipulating element, an instrument shaft having a section to be manipulated by a user, wherein the instrument shaft is coupled to the manipulating piece, further comprising a positioning element having a first rotational axis, a pulling element which is mechanically coupled to the positioning element and the section of the instrument shaft, such that a displacement of the positioning element may achieve an actuation of the section by transmitting a force via the pulling element, and further comprising an actuator coupled to the positioning element, such that an actuation of the actuator may provide for a displacement of the positioning element by transmitting a force from the actuator to the positioning element, wherein the actuator comprises a second rotational axis, and wherein the manipulating element is configured such that a user may displace the positioning element by actuating the manipulating element and wherein the manipulating element is mechanically coupled to the positioning element such that a force exerted by the user onto the manipulating element may at least be partially transferred onto the positioning element and may provide for a displacement of the positioning element.
Endoscopic instruments having a flexible or rigid endoscope shaft are used in the industry as well as in the medical field. For example, flexible endoscopes are used in veterinary medicine when performing a gastro-endoscopic examination on larger animals. These endoscopes typically have at their distal end of the endoscope shaft a distal end section which ends in an end piece. The end piece is a distal part of the endoscope which is inserted into the body under examination. Typically it comprises the distal end of endoscope optics and sometimes channels for suction, cleaning and tooling as well.
In order to obtain the largest possible flexibility regarding the spatial positioning of the end piece during examination, the end section of the endoscope shaft is typically configured to be deflectable. By deflecting or, more general, by actuating the section relative to the remaining instrument shaft, in particular by bending or curving, a piece of the instrument shaft, in particular the end piece, can be aligned as necessary. When applying deflection the user has to apply caution to ensure that no tissue surrounding the end section is damaged. It is therefore crucial that actuating the section can be controlled very precisely.
The deflection of the section is achieved for flexible and rigid endoscopes according to the prior art via a pulling element, in particular via Bowden cables. The pulling element is coupled to a positioning element, in particular a steering gear. The pulling element is typically attached to a string wheel, which is configured to hold and guide a string looped around the wheel. By actuating the manipulating element at the manipulating piece of the endoscope the positioning element is displaced. A translatory displacement of the pulling element is achieved by a rotational displacement of the positioning element. The displacement of the pulling element in turn provides for a deflection of the section.
U.S. Pat. No. 4,499,895 shows an electric endoscope which is manipulated via a lever which is coupled to the positioning element. When the lever is displaced relative to the positioning element, a bending of the lever or a change in a resistance of a potentiometer is detected and thereby a support of the positioning element via an actuator is activated. The shown arrangement, however, cannot be handled well and requires a specific releasing mechanism in order to be able to manipulate the endoscope in case of a fault.
U.S. Pat. No. 7,331,924 is directed at an electric endoscope having a deflectable distal section. The manipulation of the endoscope is achieved via a track ball which is displaced via the thumb or the finger of a user and which displacement is detected via an electric circuit. Depending on the rotational displacement of the track ball, as chosen by the user, the control of a motor is determined in a deflection control, the motor providing for a displacement of the pulling element and thus a deflection of the distal section.
The disadvantage of such an electric endoscope is, however, that its manipulation is found to be less intuitive since the manipulation of an electric endoscope, for example when coming into contact with tissue, does not provide the same feedback as the user is used to from mechanical endoscopes. The same problem is present with electric endoscopes which are controlled via a joystick. As an example, reference is made to document U.S. Pat. No. 6,932,761. Electric endoscopes further have the disadvantage that they may be hard to retract from a cavity in case of a fault when the distal section is deflected.
For mechanical endoscopes the deflection of the section is achieved only via a mechanical force exerted by the user onto a handle provided at the outside of the manipulating piece of the endoscope. To achieve this, the positioning element is typically arranged in a fixed manner on a drive shaft of the handle. When the user actuates the handle, a rotational displacement of the positioning element results and in turn a translatory displacement of the pulling element.
Purely mechanical endoscopes may require significant forces for an actuation depending on the length of the endoscope and the spatial position of the endoscope shaft. In addition, the mechanical actuation of the section automatically provides a certain resetting force in the direction of the non-deflected position (null position) of the endoscope. Further, the section provides during deflection a spring-damper-system in connection with the pulling element which stores energy during tensioning and releases energy when relaxing. This may result in a lag in the displacement when starting or an additional displacement when ending the deflection of the end section. This results in the user setting the deflection of the section in order to view a certain location may only approximately or iteratively set the deflection.
It is therefore an object of the present invention to improve an endoscopic instrument as mentioned before such that the user obtains support during manipulation as is the case for an electric actuation, without the user losing the mechanical feedback of the endoscope. It is a further object that the endoscope can be continuously manipulated even when a fault of the electronic control occurs.